This invention relates to a conveyor having rack hangers with part-carrying racks which move to predetermined transverse positions when the racks are below angled portions of the conveyor and then pivot to maintain horizontal dispositions.
The conveyor can be of the monorail type which moves racks or frames of parts or articles supported below the rail along a predetermined path. The path typically extends through cleaning and/or painting and baking operations for the parts. Since the parts are usually cleaned or coated from both sides, the part racks must be positioned parallel to the path along which they move so that opposite surfaces of the parts can be equally treated from both sides.
The monorail conveyors typically move the parts along horizontal portions of the path as well as angular ones when the parts are moved between floors or different levels of operation. When the parts move along the angled portions of the path, the racks must not touch one another, which, of necessity, requires that the racks be spaced apart a substantial distance when on the horizontal portions of the predetermined path. Heretofore,, to avoid contact of adjacent racks during forty-five degree ascending and descending portions of the path, for example,, the racks typically were spaced apart on the horizontal portions of the path a distance equal to one and one-half times the rack width.
The unique conveyor design disclosed in my U.S. Pat. No. 5,000,309, issued Mar. 19, 1991, causes the part racks or frames to automatically rotate about upright axes between positions in which they are parallel to the predetermined path when the racks are below horizontal portions of a rail of the conveyor to positions in which they are transverse to the path when the racks are below angled, ascending or descending, portions of the conveyor rail. Consequently, the racks can be almost in contact when positioned parallel to the predetermine path and below the horizontal portion of the conveyor rail. Therefore, a substantially continuous wall of parts can be presented as they pass through cleaning, painting and baking operations, for example. The throughput capacity of an existing operation including a monorail conveyor having typically forty-five degree ascending and descending portions can be increased substantially fifty percent, maintaining the same processing cycle times and changing only the feed rates of coating materials applied to the parts. The conveyor design also enables the racks or frames to be more accurately positioned parallel to the direction of the predetermined path along which they move, which is important when precise spacing between the parts and spray gun nozzles, for example, is required for uniform coating or finishing.